| Summary: | 碩士 === 國立臺灣大學 === 機械工程學研究所 === 104 === Nitinol is widely used in implantable medical devices due to its special property and outstanding biocompatibility after proper treatment. In this study, three nitinol implantable medical devices with different property requirements and applications were proposed. Aortic stent, used as a part of a novel VAD, can provide support to the T-shape transfer tube. Which allows the tube to fit the vascular wall perfectly without causing thrombosis and severe deformation. The novel VAD is able to reduce both the risk during VAD installation surgery and the time consumption for patient recovery. Spherical stent can be applied in aneurysm embolization as a less expensive option for patients due to its lower cost. Since the spherical stent can be deployed through catheter, the operation time can be significantly reduced. The spherical stents can also be applied in liver cancer treatment as not only an embolic device but a drug carrier. Both embolization and chemotherapeutic medicine can be applied at the same time to kill tumor cells. After the treatment was done, the stent can be retrieved through catheter. Recovering the blood flow of hepatic artery. The EPF needs to be enveloped by porous polymeric membrane before applied in stenting surgeries. These stenting surgeries include carotid artery, coronary arteries, bile duct, etc. The EPF can trap emboli fragments from upper stream during surgery, and prevent the blood vessel downstream from embolism.
The study has established a series of core techniques, including parametric design, finite element model, laser cutting, heat treatment and electro-polishing. Nitinol implantable devices were fist manufactured from 2mm and 7mm seamless tubes with pulsed fiber laser, followed by sequential expansion, shaping and heat treatment with designed fixtures and salt bath furnace. Finally, three devices were abraded with Al2O3 particles by-sand-blasting and then further refined by electro-polishing. Surface finish of nitinol devices improved prominently after electro-polishing, resulting in smoother edges and gentler surface undulation. Three nitinol implantable medical devices were prototyped with foregoing procedures for demonstration.
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